B777 has a Vertical Hold problem

  • I attempted a "Copilot" controlled flight in the B777 this afternoon and experienced some wild gyrations trying to maintain the set cruise altitude of FL410. I don't think the plane was ever at exactly FL410 for more than 2 seconds. It was either climbing or descend at up to 2,500 FPM constantly. I was getting Altitude Warnings up the Kazoo and an occasional AP disconnect. Heading Hold was right on the money. Climb to altitude worked just fine. Lost the flight just over half way. Bummer.


    I did notice the rigging and trim may be off a bit. An external side view has a pronounce nose up attitude when it should be more or less level. I was indicating Mach 0.89 - 0.90, 79% thrust at FL410.


    A steely-eyed Sierra Hotel record setting F-15E Strike Eagle simulator pilot. 8o
    Out now: Hawaiian Islands 8) Part 1: Kauai + Niihau v2

    Work in Progress: Part 2: Molokai, Maui, Lanai, Kohoolawe + Molokini Crater



  • Mach 0.89 to 0.90 with a supercritical aerofoil would give you upper surface shocks spreading from inboard with the centre of pressure rearwards, in real life. Is it expecting a bit much from FS2 to try so fast and so high?

    Perhaps the coffin corner is being simulated, the unprotected extreme high altitude supercritical aerofoil stall should be nasty.

  • At FL410 the max airspeed that I can fly without an overspeed warning is Mach 0.87 and 257 kts.

    But I can't replicate this issue at all and I have set turbulence to maximum now. Let me check if there is something else missing here.


    What copilot button sequence did you press?



    Edit: OK I finally got it. The copilot sets the autopilot on and then keeps telling the autopilot to engage ALT hold even though it's already in it. I told the copilot to behave better.

  • Thanks for jumping on this and finding the fix. I planned the flight path using the NAV screen, located the B777 on the departure airport runway numbers, and pressed the “takeoff icon” for the CoPilot. The “power button, Legs button, and Takeoff icons” were green. During flight only the power button and Legs were green.


    I only flew the B777, didn’t check the 747 or others.


    All flight Conditions were at default values. No or minimum turbulence.


    Those pesky inexperienced greenhorn copilots seem to always be pushing buttons and putting brakes on or confusing flaps up with gear up. You gotta keep a critical eye on them all the time. 8o


    btw, are verbal speed callouts near the top of the wish list for the heavies? Airspeed alive, 40 knots, V1, V2, Rotate, Positive rate, gear up stuff would be great.

    A steely-eyed Sierra Hotel record setting F-15E Strike Eagle simulator pilot. 8o
    Out now: Hawaiian Islands 8) Part 1: Kauai + Niihau v2

    Work in Progress: Part 2: Molokai, Maui, Lanai, Kohoolawe + Molokini Crater



  • I just checked the ALT Hold in the B777 with the CoPilot turned off. Altitude locked on as expected. Yep, needle chasing caused by CoPilot pushing buttons when he should be scanning the gauges.

    A steely-eyed Sierra Hotel record setting F-15E Strike Eagle simulator pilot. 8o
    Out now: Hawaiian Islands 8) Part 1: Kauai + Niihau v2

    Work in Progress: Part 2: Molokai, Maui, Lanai, Kohoolawe + Molokini Crater